What's the final RPM for NEMA 23 Brake stepper motor? How to caculate?

You need to post a link to the motor datasheet. Nema 23 just defines the size of the front face of the motor and the photo does not provide any data.

Also post a link to the stepper motor driver that you plan to use.

The maximum speed of a stepper motor will generally depend on the voltage at which it is driven and the load that it is expected to move. Other factors such as resonance at certain speeds, and whether you use microstepping can also affect the performance.

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